Global Change Ecology (BIO347)

Predicting the consequences of human impact a changing biosphere, implications of the lack of species knowledge.

by Trond R. Oskars

Many species and Biodiversity (1) as a whole is currently under a lot of pressure, not only climate change (2, 3, 4), but also increased direct interference by humans (5, 6, 7, 8, 9). This may lead to extinction events, severe shifts in species interactions and ecosystem composition (10, 11, 12). Due to this assessing current and past biodiversity and understanding their interactions and responses to stressors have become more important to try to predict the outcome of the ongoing human driven change of the biosphere (13, 14).

It is a known problem that there are large gaps in the fossil record (14), the older the rocks the bigger the chance that older fossils will not survive to be discovered and cannot be expected to match the diversity represented in more recent fossil assemblages (14, 15, 16). However the fossil record can still tell us a lot about long time stability of organism groups and ecosystems (14, 16), thus gives us the board picture of the effect of stressors comparable to human actions. However for a more detailed view we need data from living species (14).

Here we encounter an additional problem the lack of knowledge of extant species of many groups. About 1.2 to 1.9 million species have been formally described and given a name (17, 18). The number of species that currently exist in the world (not counting bacteria and their kin) varies by the method used, but is has been estimated as high as 8.7 million (18, 19). This leaves the majority (over 80%) of all species unknown or unnamed (20).

This opens for the possibility that species may fail to be recognized, discovered or described before being driven to extinction (13, 18). Even for relatively well known ecosystems (tropical forests) and well-studied animals (vertebrates; amphibians) there are likely still undiscovered species (18, 21, 22, 23, 24). This means that the number of undescribed species may be even higher for unexplored or inaccessible areas or taxa[1].

This also means that we in most cases know little about their roles in the ecosystem, how they interact with other species, and how the extinction may affect the ecosystem as whole.

Describing species takes a long time, averagely 21 years! (20). Much due to the shortage of taxonomists and that most species are rare and only represented by single specimens, leading to many researchers waiting until they have more specimens available[2] (20, 25). Museum collections are reservoirs of many undescribed species, sampled in bulk on long ago expeditions and many of which may already be extinct (20). Another factor is that most taxonomists don’t live in developing countries where Biodiversity is highest (20, 26). Many species can also be relatively well known by those who do live there (23), but have never been formally described or studied in other contexts. If no one has studied a species, how can we know if it is a common, widespread species or a group of similar endemic species? This is especially problematic in cases where their most well-known quality is that they are especially tasty with soy sauce (27*[3]).

How to get the impotance of proper taxonomy out to locals and legislator?

There is an additional dimension to this, what about the already described species? Does everybody agree on what a species is? (This is even further complicated by species concepts).

The problem is how we define what a species is, the method used, and the disagreement between these. Many taxonomists and sytematicists rely either on morphology or DNA to define species. Either they don’t trust one method, or they don’t have a choice, like paleontologists (28) or those researching cryptic species[4] (29).

However, In some cases convergent evolution[5] can make unrelated taxa that have some habits or habitats in common to seem closely related by morphology (30, 31) or populations that seem identical may in fact be evolutionary distinct (32) This may lead to conflict between methods and lead to bad taxonomy in the form of wrongful synonyms[6] (many taxa lumped into one) or undiscovered synonyms (one taxa counted as several). Mora et al. (18) asked 2938 taxonomists about what they felt could limit taxonomic effort[7], most answered synonyms as a major problem on the species level even if did not affect higher taxonomic levels drastically. So likely the general trends in taxa response to stressors can be trusted, but on the species level this resolution may be lacking.

How to define speices can wary form disiplines to the methods used within the disiplines.

This can be highly problematic in conservation of Biodiversity and ecosystem services. A study by Prie et al. (33) on the freshwater clams Unio in Europe, found three distinct species and several distinct sub species based on DNA. This group is riddled with synonyms based on morphology, which has impacted the conservation status of the species, leading to some of the groups to be isolated and population reduced due to human activities (33).

This lack of knowledge is dangerous as it reduces our ability to conserve species or communities that may be potentially important for ecosystem function (24, 33, 34, 35). Additionally, if enough species are not properly recognized we cannot see the complete picture of biodiversity patterns or estimate extinction rates (21, 24). It also makes it difficult to transform the scientific data into information that can be used by legislators who decide on conservation and the people who actually live alongside the species (however some manage *).

We stand to lose important ecosystem processes and services that may in turn harm other species, or even come to affect human populations (21, 34, 36, 37). Basically we don’t really know what we have lost until it is gone. Due to this it would beneficial not only to protect areas that we know to be especially biodiverse, but also areas that are relatively unexplored or less disturbed by humans, as there are likely a high diversity of undescribed species there (24).

References

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7. Brook, B. W., Sodhi, N. S., & Bradshaw, C. J. (2008). Synergies among extinction drivers under global change. Trends in Ecology & Evolution, 23(8), 453-460
8. Butchart, S. H., Walpole, M., Collen, B., Van Strien, A., Scharlemann, J. P., Almond, R. E, et al. & Carpenter, K. E. (2010). Global biodiversity: indicators of recent declines. Science, 328(5982), 1164-1168.
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17. Chapman, A. D. Numbers of living species in Australia and the world. (2009): 1-78 PP. Report for the Australian Biological Resources Study. Canberra, Australia. Available form https://www.environment.gov.au/system/files/pages/2ee3f4a1-f130-465b-9c7a-79373680a067/files/nlsaw-2nd-complete.pdf accessed on 20.02.16.
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[1] Taxa- A group of individuals or species that due to one or several methods are seen my Taxonomists or sytematicists to form one discernable unit and given a name.

[2] I have more than once spent two whole days dissecting a specimen less than 1 mm long as it was the only one available.

[3] I am revising the taxonomy of this group, current knowledge is next to none.

[4] Cryptic species- A species that is molecular distinct, but more or less impossible to separate form related species based on morphology.

[5] Convergent evolution- When evolution drives two species that are unrelated to gain a similar morphology, for example due to living in a similar habitat, also possible for related, but not closely related species trough parallel evolution.

[6] Synonymy- Basically when one taxa is regarded as the same as another and the most recent name must be replaced by the oldest available name.

[7] Taxonomic effort- Species discovery rates and to some degree the number of taxonomist working on a group (18).

Trond R. Oskars, februar 24, 2016. Ingen kommentarer til Predicting the consequences of human impact a changing biosphere, implications of the lack of species knowledge.. Category: Uncategorized. Tagged: biodiversity, coservation, missing data, taxonomy.

About Trond R. Oskars

Phd Candidate at the University Museum of Bergen. Currently working on the taxonomy and systematics of Cephalaspidea (Gastropoda: Euthyneura). Interested in the taxonomy, phylogeny and evolution of Cephalaspidea, evolution of Deep Sea species and the transission between shallow and deep habitats, convergent evolution, paralell evolution.

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